Expansible fish tail bit



Aug. 18, 1931. E. c, WEISGERBER 1,819,273

EXPNSIBLE` FISH TAIL BIT Filed June 28, 1930 as readily, Simply-ane easily expanded er co1- Patented Aug. 18, 1931 EDWIN ci WEISGERBER, or

Los ANGEL-Es, CALIFORNIA i EXPANSIBLE FisrrfrAiL rBin Y Application led lune 28, p

invention relates in general'to lish tail type -bits for drilling bore holes in the earth by the rotary method, and inoreparticularly to ex'parsible lish tail bits `for this v5 service. In other words,k this new and novel lish tail bit may be passed through a casing or bore hole of a definite size and will gen'- erate a bore hole of larger diameter'wlien rotated. That is, -it will act as a'reamer'or i0 under-reamer to enla'rge'the hole or to drill a hole larger than it may be passed through `inits nornial or collapsed position. Y

Expansible lslrtail` bits are not new in general, but in so far as I am aware they all depend upon vsome more or less complicated system of levers, springs, tapered mandr'els or eccentric mandrels to produce the change in size. This not only' makes them difficult land expensive to manufacture, but renders thenliable to 'clog or jam in use so that they cannot be operated either to produce a larger hole or to be -collapsed so that they can be withdrawn through the bore hole of smaller diameter. i lThen again, many of them areso constructed that the cutter blades are not rugged enough' to stand upunder the severe usage which they receive in producing or enlarging a. bore hole. The cutters either break ntoperso de? eli-became Se beef; thatthey winate' and the bie is useless.' l

:a is an ebjeeter my invention to overcome the above defects by providing an expansiblje rotary sa ef the ash ian type which may be lapsed and which will have no complicated parte or mechanisms te give trouble or" get out of order. I i It is another Qbject of invent-ion te proj- 40 vide an espasible rotary bit of the fish tail type which will tene to femm open in use, due to the weight of the string ofdrill pipe resting on the bit.`4 A his is a new and novel feature and inales the bit mei-'e 'positive and i5 eerltaiii its, action;

Another bjeeb of my invention isjt'p'rovide an expasible r'ta'rybit ofthe slitail typefwhieh will befpanded bythe cutting actn ef the Bit and cannet collapse inservice rne matter nos' Hard 'the femmes-law be.

' illustrates the general principles of my invenof Figure 1,'i'nthe direction of the arrowsy- 11930. serial No. 464,549.

In tlie usual type of bit expanded by rotation 'against'the surface to' be removed, theY constructionis such tha't' as fthesurface is very hard or diiiicult' tocut, the 'cutters are forced inward"4 and will not ygenerate the full ysizey 55 hole. This will"'1i`ot happen with my inl- 'pro'ved eXpan'sible bit, as it is vso constructed that it is impossible Jfor the cutt'eisto be lcrowded in to a collapsed position by thehard formation. f'

, c eo nother object of my invention is to pro- Avide a bit of the'type described in Which the cutter blades are provided with vertical wings which act as reamer blades and guides to maintain the bore hole true to size, round' 65 and straight, regardless of the presence of crevices, hard spots, rocks, etc. in thev side walls of the bore hole.

' It is another object ofmy invention to provide abit very rugged and simple in construction and inexpensive in manufacture.

My invention possess'esniany'otlier advantages, and'has other objects' which may be made more easily apparent from a consideration of one embodiment of my invention.

VFor this purpose I have shown a form in the drawings accompanying and forming part of the present specification. I shall now proceed to Vdescribe this form in detail, which f t ion; bu't it iskk to be understood that this detailed description is not to be taken in a limiting sense since the scope of my invention is best defined by the appended claims. Referrin'gto the drawings:

"Figure 1` is an elevation of the'improved bit looking directly at the cutting blades; l

Figure 2 is an elevation vof the improved bit looking at the side of the cut-ting blades Figure 3 is a bottom view of the bit showingthe blades in closed position in the full line view and in expanded or open position by the do-tted lines;

Figuree. is a section along theplane 4 4 showingthe location of thewater courses and thefrelation of the trunnion pins on the cutter blades; p y

F'gure. 5 is afsection along the plane 5- 5 A o-Figure l, in' the direction of the arrows, #911 showing the slots and keys for limiting the movement of the cutter blades; and

Figure 6 is a perspective view of one of the cutter blades with its trunnion pin.

The bit comprises a shank 10 with the usual tool joint pin 11 on the upper end thereof to connect the shank to a string of rotary drill pipe. A fluid passage 12 extends longitudinally through the pin and the shank to carry the rotary mud to the cutting face as will be described'more in detail later. The cutters 13 and 14 are mounted on the bottom of the shank 10 in a new and novel manner.

Each cutter has an effective width which is approximately one-half the diameter of the bore hole to be produced by the bit, and is preferably of a greater height than width. Each cutter is V-shaped in horizontal section. One leg 15 of the V is approximately straight while the other or outer leg 16 is curved and joined to the leg 15 at their converging point by a curved portion 17. The two wings of the cutter are joined at the top by a head 18 which projects beyond the blade adjacent the straight portion thereof.

The upper surface 19 of this head is a plane surface formed at an angle with the main axis of the cutters such that, when the cutters are in their vertical working position, the portion of the plane surface adjacent the axis of the bit is lower than thel portion farthest removed from the axis. When the cutters are placed in operating position, the two adjoining plane surfaces form a flat V, and the lower end of the shank has twocorresponding plane surfaces 20 and 21, against which the plane surfaces of the cutters bear.

A trunnion pin 22 is formed on each of the surfaces 19 and normal thereto. rThis trunnion pin is located near one edge of the surface adjacent the straight side of the cutter. Inclined bosses 23 and 24 are formed'on opposite sides of the shank, at the lower end thereof, and the trunnion pins 22 on the cutters are mounted in holes 25 and 26 which extend lengthwise through the bosses. These trunnion pins 22 are free to turn in the bosses, and are held against longitudinal movement by any usual means at the upper end of the boss. I have illustrated the boss .Y as having a flat surface 27 at the upper end,

(see Fig. 2) against which a pin 28, through the trunnion pin 22, bears. Obviously any other common means may be used, such as a nut and washers on the upper end of the pin, a split bushing under a collar on the upper end of the pin, or any similar and commonly used locking device. Y

The rotation of the cutter and trunnion pin, with respect to the shank, is limited by a key 27 on the plane surface 19 adjacent the trunnion pin 22. This key lies in a recess v28 in the lower end of the boss. I The recess is wider than the key, as shown in Figure 5,

so that the trunnion pin 22 is free to turn a predetermined amount in the boss.

When the cutters are in place on the shank in their normal or retracted position, as shown by the full lines in Figure 3, the two straight surfaces 15 lie in essentially the same plane through the center of the shank, while the curved surfaces 16 lie adjacent the walls of the hole 29. The leading edges 30 and 31 are in contact with the circle 29, but the curved outer surfaces 32 and 33, back of the leading edges lie inside the circle 29 to provide a suitable clearance for the bit.

When the bit is rotated in a clockwise direction in the hole, which is the direction of rotation when drilling, the cutters assume an expanded position, asshown by the dotted lines in Figure 3, and the bit will generate a circle 34 of a greaterdiameter than the circle 29, through which the collapsed bit can pass..

This expanding action takes place due to the slight rotation of the cutters about the axes of the trunnion pins 22, which are eccentric to the main axis of the cutters, and therefore throws the leading edge 30 outward.

The cutters will maintain this expanded position while cutting, due to the fact that all the thrust of the formation on the cutter is applied on one side of the axis of rotation, so that there is nothing to force the cutter towards contracted position. Another factor which tends to maintain the cutters in expanded position, is the fact thatfthe bearing surface between the cutters and the shank is inclined to the vertical and so located with respect to the axis of rotation of the blades on the shank, that the weight of the shank and string of drill pipe tends to slide the shank down on the inclined surface, which rotates the cutter about the axis of the trunnion pin. The amount of rotation of the cutter blades is limited bythe freedomxof motion, or clearance, allowed the key 27 in the recess 28.

As soon as the bit is picked up olf the bottom of the bore, the mass of the cutter blades tends to slide them downward along the inclined bearingV surface and so rotate the blades back to the original full lined collapsed position, shown in Figure 3. If it is considered advisable to make doubly sure that the cutter blades have resumed the collapsed position, the bit may be rotated a few turns in a counter-clockwise direction, after being lifted olf bottom. This will turn the cutter blades to the collapsed position, and the bit may then be withdrawn through the casing or smaller bore hole. l

The main watercourse 12 is divided near the lower Aend of the shank into two water courses 35 and v36, which terminate in openings 37 and 38 just above the cutting face of each blade. VUnder some conditions it may be deemed advisable to extend the water 'course to av single opening inthe center of K V'or projection would l abut agains'tfa yshoulder .on the lower end of the shank,l andliniit the ings.

the lower end of the shank, between the two cutter blades, or thek central opening may be used in connection with the two laterall open- Instead of using the'ikeyQ to limitA the rotation of the cutters' with'respect'` to the shank, a projection or .lip` could bezformed on the end of the surface- 19 :atv the. point farthest. from ythe trunnion pin 22. 'A This lip rotation ofthe cutter withV respect'l to the shank. Other usual vand commonly used means may beV employed to limit the movement of the cutters. y v

To recapitulate, the cutters are kmoved to the collapsed position 'and theV bit lowered through a casing or open bore-hole. When the bit is rotated in a right-hand, or clockwise direction with the cutters in Contact with the side or; bottom ofthe bore-hole, the cutter blades will rotate a predetermined amount ,with respect to the shank of thev bit and expand to produce a bore-,holey of greater diameter than that through which the bit was lowered.y When it is desired ,to raise the bit throughthe smaller Vbore-hole, the bit is lifted off of the bottom and rotated slightly to the left. This rotates the cutter blades in the opposite direction, with respect to the shank, and collapses thebit' to itsminimum diameter. y

Then the'cutter vblades becomedull they may be ren'ioved from the shank by'simply removing theholding means 28 at the top of the boss on the shank and sliding the' trunnion pin 22 out of the boss 23, 245A new sharp cutter` is quickly slipped in place and locked and thebit ready for service again without the necessity of removing the "bit from the drill pipe. f If it should be desirable to change the size of thehole that the' bit will generate, it is donequicklyand,easily by changing the' cutter blades for ones `of the required width. f

The majority of cutting is doneby the u lower edge of the face 15 while the leading edge of the curved face 16 acts as a reamer vtokkeep the hole true to size and also as a guide to maintain the bore hole straight and true, which is a very desirable feature. K

Iclaim: L Y u 1. In an expansible rotary lbit having a shank land means at the upper end thereof adapted to attach the shank to a. string' of drill pipe; a plurality of inclined bearing surfaces formed on the lower end of the shank, a plurality of cutters having inclined bearing surfaces adapted to cooperate with the rst named bearing surfaces, whereby a weight on the shank will tend to separate said second named surfaces and cause a rotation of the cutters to expand them.

2. In an expansible rotary bit having a shank; a plurality of inclined bearing` surshank.

faces formedon the lower end of the shank, aplurality of cutters having upper inclined bearing surfaces rotatable against saidflrst named surfaces whereby a weight on the shank vwill tend to separate said second named surfaces and cause a rotation of the vcutters to expand them, said cutters being to attach the shank to astring of drill pipe;

a Vplurality of plane surfaces formed on the lower end of said shank, eachv of said plane surfaces forming anobtuse angle with aplane through the axisof said shank';"a

blade type cutter rotatably mounted on each of said `plane ysurfaces whereby the axis of' the cutter is maintained substantially parallel to the'axis ofthe shank.

4f.v In a rotary bit having a shank and meansv at the upper end thereof adapted to attach the lshank toa string of drill pipe; a pluralityof plane surfaces formed on the lower endof said shank, each forming an obtuse angle with a plane through the axis of said shank; said plane surfacesintersecting on the axis of saidshank; a cutter rotatably mounted on each of said plane surfaces whereby the axis Vof the cutter is maintained substantially parallel to the axis'of the shank; and means adapted to restrict the rotation of each cutter within certain predetermined limits with respect lto the 5. In a rotary bit having a shank and means at the upper end thereof adapted to attach the shank to a string of drill pipe; a

plurality of'cutters trunnioned on the lower end of said shank, said cutters being eccen- `trically mounted on said trunnions; and

means adapted to restrict the rotation of limits with respect to said shank. y

6. In a rotary bit having a shank and means at the upper end thereof adapted to attach the shank to a. string of drill pipe; a

plurality of plane surfaces formed on the lower end of saidy shank, and intersecting on the axis of said shank, each plane surface 'forming an obtuse angle with the axis of said shank; a cutter trunnioned on each of said plane surfaces, said cutter being eccentric on said trunnionyand means adapted to restrict the rotation of each cutter within certain predetermined limits with respect to said shank.l

'7. In a rotary bit having a shank and means vatthe upper end thereof adapted to attach the shank to a string of drill pipe;

yay plurality of plane surfaces formed on the lower end of said shank and intersecting on the axis of said shank, each plane sur'- face forming an obtuse angle with the axis thereto,

of said shank; a cutter rotatably mounted on each of said plane surfaces and having its axis parallel with the axis of said shank; and means adapted to restrict the movevment of said cutter within certain predetermined limits with respect to said shank.

8. In a rotary bit having a shank and means at the upper end thereof adapted to attach the shank to a string lof drill pipe; a plurality of plane surfaces formed on the lower end of said shank and intersecting on the axis of said shank, each plane surface vforming an obtuse angle with the axis of said shank; a cutter trunnioned on each of said plane surfaces and having its axis parallel with the axis of said shank; said trunnion being eccentric with regard to the axis of said cutter; and means adapted to restrict the' movement of said cutter within certain prevdetermined limits with respect to said shank.

9. In a rotary bit Ahaving a shank and .means at the upper end thereof adapted to attach the shank to a string of drill pipe; a plurality of plane surfaces formed on the lower end of said shank andintersecting on the axis of said shank, each plane surface forming an obtuse angle with the axis of said shank; a cutter trunnioned on each of said plane surfaces and having its axis parallel with theaxis of said shank; said trunnion being eccentric with regard to the axis of said cutter and normal to said plane surface; and means adapted to restrict the movement of said cutter within certain predetermined limits with respect to said shank.

10. In an expansible rotary bit having a shank and means at the upper end thereof adaptedA to attach the shank to a'string of drill pipe; a plurality of plane surfaces formed on the lower end of said shank and intersecting on the axis of said shank, each plane surface forming an obtuse angle with `the axis o f said shank; a cutter trunnioned on each of said plane surfaces for rotation within predetermined limits with respect said cutter being eccentrically mounted on said trunnion whereby said cutters describe a circle of greater diameter in one position than they do in the other posi tions. c

11. In a rotary bit having ashank vand means at the upper end thereof adapted to attach the shank to a string of drill pipe; a plurality ofplane surfaces formed on the lower end of said shank and intersecting on the axis of said shank, eaclrplane surface forming an obtuse angle with the axis of said shank; a V type cutter trunnioned on each of said plane surfaces and having its axis parallel withthe axis of said shank; and means adapted to restrict the movement of said cutter within certain predetermined limits with respect'to said shank.

12. In an expansible rotary bit having a shank and means at the upper end thereof .by said bit is varied as and for the purpose specified. y v

13. In an expansible yrotary bit having a shank and means at the upper end thereof adapted to attach theV shank to a string of drill pipe; a plurality of plane surfaces formed on the lower end of said shank and intersecting on the axis of said shank, each plane surface forming an obtuse angle with the axis of said shank; a cutter eccentrically trunnioned on each of said plane surfaces for rotation within predetermined limits with Arespect thereto, and having its axis parallel with the axis of said shank, whereby the diameter of the circle generated by said bit Vis varied,

14. In an expansible rotary bit having a shank and means at the upper end thereof adapted to attach the shank to a string of drill pipe; a plurality of plane surfaces formed on the lower endof said shank and intersecting on the axis of said shank, each Vplane surface forming an obtuse angle with the axis of said shank; a trunnion pin in each of said plane surfaces and normal thereto; a cutter eccentrically mounted on each of said trunnion pins and having its axis parallel with the axis of said shank, and co-operating means on said shank and said cutter adapted to limit the rotation of said cutter with respect to said shank.

15. In an expansible rotary bit having a shank and means at the upper end thereof adapted to attach the shank to a string of drill pipe; a plurality of plane surfaces formed on the lower end of said shank and intersecting on the axis of said shank, each plane surface forming an obtuse angle with the axis of said shank; a trunnion pin in each of said plane surfaces and normal thereto; a V-shaped cutter eccentrically mounted on each of said trunnion pins and having its axis parallel with the axis of said shank, and cooperating means on said shank and said cutter adapted to limit the rotation of said cutter with respect to said shank.

In testimony whereof, I have subscribed my name.

EDWIN C. WEISGERBER. 

